


The new potions teacher

by Thrandolawlu



Category: One Piece
Genre: Alternate Universe - Harry Potter Setting, Fluff and Smut, Lemon, M/M, Porn With Plot
Language: English
Status: Completed
Published: 2020-08-12
Updated: 2020-08-12
Packaged: 2021-03-06 06:01:24
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,505
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25858597
Author URL: https://archiveofourown.org/users/Thrandolawlu/pseuds/Thrandolawlu
Summary: Law is the new potions teacher and accepts to tutor Luffy, both give into their desires when a potion backfires.
Relationships: Monkey D. Luffy/Trafalgar D. Water Law
Comments: 11
Kudos: 87





	The new potions teacher

**Author's Note:**

> This story is set in the universe of the Harry Potter and the Deathly Hallows.  
> Their ages are pre-time skip, Law is 24 and Luffy 17.  
> But I changed the ages of Sanji, Zoro, Nami and Usopp to make them 17 like Luffy.  
> Luffy is an adult as the age majority in the wizarding world is 17.
> 
> I am a beginner so I hope you enjoy this work. English is not my native language so I am sorry for any mistakes.  
> Lastly, I don't own One Piece and I didn't copy this work from anyone.

Luffy was at King’s Cross station on platform 9 ¾ hugging Ace goodbye. “Take care Lu, and remember, don’t go looking for trouble” Ace said as he let go of his brother.  
Luffy gave his brother a wide grin “I will try” he said. As the whistle announcing the train’s departure resounded on the platform he jumped into the Hogwarts Express and stood by the door waving goodbye to his brother. Once the train started gathering speed, he walked along the corridor making his way to the compartment where his friends were waiting for him. Opening the door of the compartment, he took the sit next to Sanji and started going through his bag looking for the lunch Ace had packed him.

This was Luffy’s last year at Hogwarts, he was excited to be finally graduating but the thought of not being able to do so with all of his friends filled him with sadness. Now that the Dark Lord, Donquixote Doflamingo, had returned and was in control of the Ministry of magic, it was a requirement for every student in Hogwarts to prove that they were of wizard descent in order to be allowed to attend the school year. When the announcement was made Luffy had been furious, he had immediately considered dropping out and go into hiding with Nami and Usopp that were muggle-born. But after much convincing from Ace and Sabo he decided to attend school. After all, he only had one year left before graduating and he needed to pass his N.E.W.T.s to fulfill his dream of becoming the best auror in the world. Hopefully, Sanji and Zoro had also decided to attend school this year, well Sanji didn’t really have a choice as his father decided for him but it was good to have them there with him.

The journey to the school was spent laughing and eating. They arrived to Hogsmead at nightfall and made their way out of the train and into the carriages. Once they reached the castle’s gates they walked towards the great hall and quickly grabbed a seat at the Griffindor table. The sorting of the first years started and, as seconds passed, Luffy was getting impatient and hungrier, as if on cue his stomach started to grumble. The welcoming feast had been in his mind all day and he couldn’t wait any longer for the food to materialize. Finally, when last first year was being sorted he readied himself with his knife and fork, but to his disappointment, the new headmaster and previous potions teacher, Donquixote Rocinante, decided to say a few words.  
"Welcome to a new year at Hogwarts! Before we begin eating, I would like to introduce you to your new potions teacher, Trafalgar Law” he said his hand showing the person sitting on his right. The new teacher was devilishly handsome. He had tanned skin, tousled jet black hair and his eyes were a mesmerizing golden honey hue with deep shadows underneath, making him look as if he had had too many sleepless nights. His face was strong and framed by sideburns and his well-defined chin was obscured by a goatee. At his introduction Law’s lips were drawn into a hard line and he scowled at the students. “I am sure you will learn a lot from him. He will also be in charge of the hospital wing as he is a certified healer. Now DIG IN!” he finished with a grin and immediately the tables were overflowing with food.

Chatter erupted all over the hall as students turned their attention to the feast in front of them but Luffy’s fork and knife laid abandoned on the table, his gaze intently fixed on Law. This went on for a few minutes until Sanji and Zoro realized that food was not disappearing at the usual rate, they turned their heads to find Luffy staring at the staff table. “Luffy! Luffy! LUFFY FOOD!!” Sanji’s yells finally got the raven hair’s attention “Right… dinner…” he said still lost in thoughts. “So a new potions teacher huh” Sanji said giving him a knowing look “Yeah…” Luffy felt his cheeks heat up under the intensity of Sanji’s stare and proceeded to shove as much food as possible in his mouth in an attempt to hide his blush from his friends. As Luffy struggled to swallow his food, he felt surprise at his behavior, it was the first time he had ignored food. But somehow, he couldn’t take his eyes away from the new teacher ‘Trafo-… Tarafla-… Torao’. Even now, he wanted to turn his head again towards the staff table to look at him and engrave every detail of Torao’s face into his mind, the color of his skin, his side burns, the little goatee, the golden eyes… He was fighting the urge to turn his head again but decided against it as Sanji and Zoro kept throwing him strange looks.  
That night, for the first time in his life, something other than food was on his mind as he was falling asleep. He couldn’t stop thinking about the tall, dark and handsome man sitting at the staff table.

The next morning at breakfast the new teacher was on everyone’s lips, the girls at the table were swooning over him and were constantly talking about how handsome he was. For some strange reason this made Luffy really annoyed, he tuned out of the conversation around him and started angrily shoving bacon into his mouth, somehow his mood was ruined. But a few moments later when he received his class schedule his mood considerably improved as he noticed that his very first lesson today was potions. For once he was grateful that Sanji and Zoro were not taking that class, because that meant that he would be able to stare unabashedly at Torao during the whole class without his two friends noticing. He still had half an hour before the start of the class but he wanted to make sure to have a front row sit so he said goodbye to his friends and made his way down to the dungeons. When he arrived the classroom doors where closed so he leaned against the wall and decided to wait, soon he was joined in line by Coby.

As they were chatting the hall became crowded with students and Luffy couldn’t help but listen into some of the conversations having place around him. “… the rumor is that he was responsible for those nasty incidents a couple of years ago. I remember my bother telling me about the 7th year slytherin with the words ‘DEATH’ tattooed on his fingers who liked to experiment on other students. He would use this weird spell to take their hearts out without killing them […]” “[…] I swear I saw tattoos on his fingers […]” “[…] the guy was never expelled nor punished and they say that he moved to experimenting on muggles. But sometimes dismembered students could be found around the castle, that is how the legend about the surgeon of death started […]” ”[…] so creepy […]”. Luffy was going to ask who they were talking about, but was distracted as the doors opened. His question was forgotten as his mind was focused on entering the classroom quickly as possible to grab a sit by the front. He shouldn’t have worried so much though, even if the teacher was handsome the rumors of him being the surgeon of death had spread like fire since the feast and no one was keen to be near him, so Luffy was the only student sitting in the front row.

Law was sitting at his desk reading a book and not bothering to look at the students as they started to fill in the classroom. Luffy focused his whole attention on the man before him, being closer he could take in more details about his appearance. Both of his ears were pierced and he had two golden hoops in each ear and both of his hands had tattoos, he could see a cross in the back of the hand and the letters D E A T H on his fingers. He wondered if more tattoos could be seen beneath the black robe he was wearing, Luffy blushed at this, what was he thinking! Law put his book down and stood up “Today we will start by making a simple potion because I want to know everyone’s level before we move to more complicated things. I expect you all to perform at a high level so today’s lesson should not be a challenge”. With those words the lesson started and all the students busied themselves for the next two hours.

By the end of the lesson, Luffy was a mess, blood was oozing from a cut on his head and he had several burns on his hands. The class had been a disaster. It all started with him staring at Law for a full 15 minutes before the later came up to his desk to ask him why he hadn’t started preparing the potion as instructed. At that Luffy’s face became red like a tomato and he bumped his head against the desk when he hurried to get his things out of his bag and onto the table. During the rest of the lesson he had been so distracted by Law that he kept misreading the instructions and adding the wrong ingredient at the wrong time causing the contents to bubble furiously. Unfortunately for him, not following the instructions resulted in Law spending even more time by his desk as he kept going over the different steps with him. Law also had to help him clean his things after the contents of his cauldron splashed all over the table and even got on his hands leaving angry red marks. Being on the receiving end of constant attention from Law made Luffy so flustered that when the bell rang he ran away without bothering to pick up his things. He made it all the way to the main entrance before he realized he didn’t have his things and had no idea what his next class was. Taking a couple of breaths he forced himself to calm down before reluctantly making his way back to the potions classroom. He sighed as he walked down the corridor, he was feeling mortified by his behavior, he had never acted like this before. But somehow when he was near Torao he became a blushing mess and could barely think straight.

Back in the classroom Law was sensing an oncoming headache, he couldn’t believe someone lacking so much skill for potions had made it into his N.E.W.T level class. It had to be a mistake, the teen had needed his constant attention and even with his help he hadn’t been able to produce a decent potion. He frowned as he looked at the mess Luffy had made on the table. He took out his wand and with a flick the things on the desk started to move and find their way into the backpack laying open on the floor. Once everything was back in the right place he took the bag and closed it, noticing a mini straw hat keychain hanging from the front pocket. He was wondering whether to wait for the kid to come back for his bag or to leave it in the classroom when Luffy appeared at the door. “Professor Torao I am sorry” he said his whole face expanded into a beaming grin. Law was taken aback by the softness in his eyes and the gentleness in his smile. As the student approached, he was able to take on more of his appearance. During the class Law had been too busy trying to prevent a disaster from happening to properly look at the teen, but now that he had him in front, the more he looked, the better he got. On either side of his button nose were two bright eyes the color of rich chocolate, each framed by eyelashes so long it should be illegal. His head was covered by unruly raven black locks and a slight blush adorned his cheeks. Law collected himself as he spoke “Mugiwara-ya, it’s Professor Trafalgar, not Torao” “Mugiwara? … oooh because of my keychain! I am Monkey D. Luffy, and I prefer Torao, so that’s what I will call you”. Law was going to correct him again when he noticed a drop of blood threatening to come out of a gash on Luffy’s forehead. He decided to momentarily drop the fight regarding his name as he went into healer mode. He grabbed Luffy’s wrist and pulled him towards his desk. “Mugiwara-ya sit on the desk and don’t move” he said while fumbling the contents of his top drawer. He found the first aid kit and opened it and took some cotton and a vial. “O-okay…” Luffy blushed furiously as Law’s face came closer to his, he felt a sting as the teacher dabbed a wet cotton on his wound but he was too busy breathing in Torao’s scent to care. He smelt heavenly, like a forest after a rainy day with hints of fresh pine and coffee. The smell was like a drug to Luffy, he couldn’t get enough of it and almost whined when Law pulled back. “I cleaned your wound, you have to be more careful” Luffy moved his hand towards the bandage on his forehead “Don’t touch it!”. He saw Law’s eyes widen at the sight of his hands “What happened to your hands?” Law asked as he delicately took Luffy’s hand into his and examined the angry red marks. “I got burned when the potion splashed on the table” the teen answered. Law took another small vial from the first aid kit and spread the ointment it contained on the red marks “this will help, come to see me if the marks don’t go away. Who knows what type of poison you brewed in that cauldron of yours… Now go or you will be late for your next class” “Thanks Torao!” Luffy gave him his brightest grin and left the classroom running.

Little did Law know that he would come to regret his small act of kindness.

One month later

Law was sitting at his desk enjoying a cup of coffee while he graded some essays. Law’s office could be described as gloomy but he loved it, the room was dimly lit and the walls were lined with bookshelves that where either bursting with books, or, with large glass jars filled with the hearts of different creatures. To some, the organs could be qualified as slimy and revolting but to Law they were the most beautiful thing ever created, he could spend hours studying each one in detail. When he finished grading the essays he started preparing his next lesson which was with the 7th years. He thought about Luffy, this past month his performance remained abysmal. Law had checked his grades from previous years and had been surprised to see that they were actually good, so he couldn’t understand why the teen couldn’t complete any of assignments. Sure, he had improved since the first class but that was not surprising given the amount of time Law spent going over the instructions with him. But soon the class would be moving to more advanced potions and more students would need his help, so he wasn’t sure that Luffy would be able to keep up. They would need to have a serious talk.

At that exact moment Luffy came bursting through his office door “Torao!” Law opened the first aid kit laying on his desk and started taking out the contents “What is it this time Mugiwara-ya?” he asked. “Nothing, I just didn’t see you at lunch so I came to bring you some onigiri and make sure you don’t skip lunch”. Law sighed as he put everything back into the first aid kit “Thanks but I can take care of myself” “You say that but there are days where you only have coffee and no food, the elves told me! Food is important you know!” Luffy said his lips forming a pout. “Now you have elves stalking me!” he rolled his eyes but grabbed an onigiri from Luffy’s hand and bit into it. “Well Professor Roci came up with the idea but we have to, otherwise you won’t take care of yourself” Luffy started pacing around the office looking at the jars “Oh you have a new one! Let’s see what the label says, Kappa, it looks really cool and oooh it’s still beating!”.

This scene had become a common occurrence as Luffy had taken to coming to Law’s office every day. At first he came only when he was in need of medical attention, which was almost every day as the teenager was constantly getting injured during quidditch practice. Law had told him to go to the hospital wing but he insisted on seeing ‘Torao’ on account that ‘that creep Caesar creeped him out’. But recently he was coming every day, he would bring food, interesting creatures he found in the forbidden forest or just share a weird story about his friends. In the beginning, Law had tried to kick him out when he came without any injury but his complaints fell on deaf ears. Also, he suspected that Cora-san played an important role in encouraging those purposeless visits ever since the tall blonde had walked into his office while he was bandaging Luffy’s wounds. To be honest, Law was not as annoyed as he liked to pretend to be, more than once he had found himself looking forward to the visits and laughing at Luffy’s antics.   
Luffy was getting more and more comfortable around Torao the more he spent time with him. Now he was able to act normally in his presence even though his body still reacted strongly, especially if the teacher touched him. For example, whenever he saw Law, Luffy’s heart would start to beat so hard he thought it might come out. And when he touched Law, he felt as if a swarm of pixies had been let loose in his stomach.

“Luffy-ya” Luffy turned to look at Law, his stomach making a flip, it was the first time the teacher used his name. “We have to talk about your performance in potions. Our class will soon be moving to advanced potions and I am not sure you can keep up. You may want to consider dropping the class and taking herbology instead”. Luffy’s heart sank at this and his face took on a serious expression “No Torao, I am going to become the best auror in the world so I will pass my potions N.E.W.T”, Law was surprised by Luffy’s seriousness, he had never seen the teen make such an expression “Luffy-ya, it has been a month and you have not been able to correctly do any potion so far”. Luffy’s expression remained unchanged as he repeated “I will pass and I will become the best auror in the world” Law tried a different strategy “Hmm maybe one of your friends can tutor you”. At the suggestion, the teenager’s eyes shone and a mischievous grin spread on his face “I know! Torao why don’t you tutor me!”. Law’s mouth fell open “I-I am very busy with classes and the hospital wing Luffy-ya, I don’t know when we could find the time…”. The teenager looked at Law with bright eyes full of hope “Please Torao, you are the best teacher ever, I have already improved so much thanks to you”. Looking into Luffy’s hopeful eyes Law couldn’t find it in him to refuse and saw his resistance crumbling “Ok, but you have to be serious about this. If you haven’t improved in one month you will have to drop out”. Luffy cheered and launched himself at Law hugging him tightly “Thanks Torao! I promise I will do my best!”. Luffy’s arms were soft, yet strong and Law melted into the embrace. The feeling of the teen’s body pressed against him made his stomach flutter. And before he knew it, the hug ended as abruptly as it had begun. The student detached himself and sprinted out of the office, worried that if he stayed too long the older man would take back his offer.   
The tattooed man stood there feeling stunned, he had almost hugged the teen back not wanting the moment to end.

The following Friday after dinner Luffy made his way towards Law’s office for his first tutoring session. He stopped in front of the door and forced himself to calm down. He needed to get himself together and act normal in Torao’s presence if he wanted to keep potions for his N.E.W.T.s. He took one last breath and turned the knob.

Law was sitting by the fire reading a book, “Torao! I am here”. The teacher put down his book and made his way towards the desk “I prepared a cauldron, take out your potion ingredients and open your book page 14. Today you will be making the Draught of Peace, it’s an O.W.L level potion so I expect you to be able to make it. You will need to follow the instructions very carefully, any mistake can have drastic consequences”. “Adding too much of the ingredients can put the drinker into a heavy, sometimes irreversible sleep” the teen recited. “Someone is taking the tutoring classes seriously” Law said, a smirk tugging at the corner of his lips. “The first ingredient you will need to add is powdered moonstone, what can you tell me about the usage of this ingredient in potion-making?” “Powdered moonstone is one of the ingredients used in the Draught of Peace, Potion #86 and love potions” “Correct, now start adding the ingredients and carefully follow the instructions”.

Luffy read the instructions, ‘Add powdered moonstone until the potion turns green.’   
The raven head added the powder and watched as his potion turned green. He then stirred the potion until it turned blue.   
Law came close to him to peer into the cauldron “Good”, at the closeness Luffy caught the teacher’s smell and was transported back to when he had hugged him a few days earlier. Having his head buried into Torao’s chest and being surrounded by his smell and warmth had felt divine. The moment had been too short and he longed to touch Torao again. Suddenly, as he read the next step ‘Add powdered moonstone until the potion turns purple’ an idea came to him. He took the shaker containing the moonstone powder and sprinkled it on the potion until it became a deep blue color almost purple, then, he unscrewed the lid of the shaker and placed it loosely on top.   
Law came to check again on Luffy’s progress and reacted at the bluish color “hmm I think you need to add just a little more”. Luffy watched nervously as Law’s hand closed around the shaker. He held his breath as the teacher hesitated slightly before lifting the container, then watched as Law’s hand moved to sprinkle the powder into the potion. As expected, the lid fell off into the caldron followed by the entire contents of the shaker. A pink cloud rose from the cauldron and engulfed the entire office.

As the smoke dissipated they stood near the desk gazing at each other. Their gaze lasted for a second but was enough to take in the other’s lustful appearance. Everything about them screamed desire. Eyes dark with lust, cheeks blushed and lips slightly parted and panting. At the sight of Luffy something stirred in Law and took over his mind, all the reasons not to give into his desire were forgotten. The only thing that mattered was touching him, kissing him and making him his. Law moved forward and grabbed Luffy by the waist, pulling him close against his chest. The teen inhaled sharply as a tattooed hand glided through his messy hair. Law leaned in closing the gap between their lips and covering Luffy’s mouth with a hungry kiss. The way their lips connected was magical, waves of pure pleasure were running through their bodies. When a soft moan escaped Luffy’s lips, Law slipped his tongue into the teen’s mouth, turning the kiss more passionate by the second. Luffy felt himself being lifted onto the desk, Law’s body pressing between his legs, grinding their crotches together. They started tugging at each other’s clothes almost ripping them off. Their shirts began to hang loosely and Luffy slipped a hand under Law’s shirt scratching against the skin of his chest. The teacher grunted at the feeling and locked their mouths tighter, making the kiss greedier. Before they knew it they were naked, “I love your tattoos” Luffy’s hands were roaming all over Law’s chest, tracing the black inked lines with his fingers, making the older male shudder under his touch. “You are so beautiful” Law whispered into Luffy’s ear before trailing kisses down his neck and biting the soft skin, causing the teen to arch his back and moan loudly “Aaah- Torao”. The tattooed male settled himself between Luffy’s legs nipping and sucking at his inner thighs before taking his cock into his mouth. “Aaaah nghhh” at the sensation a loud moan escaped Luffy’s lips, he felt as if he was in heaven. But his moans where muffled when three fingers where shoved into his mouth, he could read the letters E.A.T. on each of the fingers. “Make them wet” Luffy obeyed moving his tongue between the digits. Law’s mouth left Luffy’s cock and the teenager started to whined at the loss of heat but his complaints turned into a new moan as the teacher started licking at his entrance “No… please… To-Tora-oooohhh” “Mmmm you taste so sweet” Luffy’s moans intensified at the continued ministrations and he was sent over the edge when the wet fingers made their way inside him. “I-I-I-aaghhhh” Luffy’s eyes rolled back as he came hard, cum spurting all over his stomach. Without giving him time to recover, Law pushed Luffy against the desk making him lay on his back. After having performed a lubricating spell, he lined his cock against the teen’s entrance and entered him. Luffy whimpered softly at the feeling but recovered as Law started moving slowly in and out of him. Law’s thrusts intensified when he felt Luffy move to match every thrust. Law lost when he found Luffy’s sweet spot “Law-La-ahhnghhhhhh-aw”. The sight of the teen falling apart beneath him sent him to the edge and he climaxed together with Luffy. They collapsed into each other as they regained their breath.

Their first tutoring session had ended in hot steamy sex due to a Draught of Peace potion backfiring. Law felt guilty because he had realized the lid of the container was loose and he knew what would happen if too much moonstone powder was added.


End file.
